In the development of wireless communication systems, techniques of interworking between a cellular wide-area communication system and a non-cellular local-area communication system receive attention. In this regard, a specific issue relates to traffic offloading from a cellular wide-area communication system to a non-cellular local-area communication system. Thereby, an operator of a cellular wide-area communication system operating on a licensed band is enabled to additionally utilize an unlicensed band so as to efficiently increase bandwidth and throughput and/or enhance system coverage and performance. Such unlicensed band may be any ISM (industrial, scientific and medical) radio band usable for license-free error-tolerant communication applications such as Wireless LAN (WLAN) or cordless (e.g. DECT) telephony, e.g. the 915 MHz band, the 2.450 GHz band and the 5.8 GHz band.
Generally, any (licensed) band and any communication/connectivity technology operable on such (licensed) band can be used at the source side for such traffic offloading in the meaning of the present specification. That is, any reference made to LTE, LTE-A, UTRA or the like merely relates to a non-limiting example used for illustrative purposes only. Similarly, any (license-free) band and any communication/connectivity technology operable on such (license-free) band can be used at the target side for such traffic offloading in the meaning of the present specification. That is, any reference made to WLAN, DECT, or the like merely relates to a non-limiting example used for illustrative purposes only.
Hereinafter, reference is mainly made to an LTE/LTE-A system as an illustrative and non-limiting example of a cellular wide-area communication system, while an UTRA system and a non-3GPP communication system represent another non-limiting example in this regard. Further, reference is mainly made to a WLAN (or WiFi) system as an illustrative and non-limiting example of non-cellular local-area communication system, while a cordless phone system represents another non-limiting example in this regard. It is to be noted that such references are made by way of example only, and similar considerations as outlined hereinafter equally apply to other types of cellular wide-area and non-cellular local-area communication systems accordingly. Further, it is noted that WiFi as used herein is meant to refer to at least any connectivity technology addressed by the WiFi Alliance, including wireless local area networks (WLAN) based on the IEEE 802.11, which is a set of standards carrying out WLAN communication in different frequency bands (e.g. IEEE 802.11b and 802.11g/n on the 2.45 GHz ISM band, IEEE 802.11a/n/ac on the 5.8 GHz ISM band, etc.)
Recent growth in data traffic driven by mobile applications on smart phone devices, tablets, etc. has continued to strain the capacity of today's cellular networks. Therefore, network operators are increasingly utilizing unlicensed WiFi spectrum to cope with such network congestion, and this trend is expected to accelerate further as traffic demand continues to grow.
The use of unlicensed spectrum is a cost-effective approach to add the needed capacity for today's cellular networks, given the limited availability and high cost of licensed spectrum. Currently, WLAN/WiFi is integrated as a separate access network to the core network of cellular systems, such as the 3GPP EPC. This requires extra cost of deploying the complete WLAN/WiFi access network and also impacts the 3GPP core network entities. Existing WLAN/WiFi offloading solutions are based on this deployment model of distinct 3GPP and WLAN/WiFi access networks using a common core network with selective switching of flows based on operator/user policies. That is to say, LTE/UTRA-WiFi interworking is currently supported at the core network (CN) level only.
However, another deployment solution would be preferable, which results in a tighter integration and aggregation of 3GPP access network components with WLAN/WiFi access networks without any impact to and reusing the same 3GPP core network elements. That is to say, support of LTE/UTRA-WiFi interworking at the radio access network (RAN) level would be desirable.
Thus, there is a need to enable information exchange for cellular non-cellular interworking such as for example LTE/UTRA-WiFi interworking at the radio access network (RAN) level.